java代码中文件下载

一、文件下载

@RequestMapping(value="/download")
	public void download(ModelAndView mav, HttpServletRequest request,
			HttpServletResponse response, @RequestParam(value="id",required=true) String id) {
		
		Datadownload data = null;
		
		//根据id获得资料对象
		data = datadownloadSelectService.getByID(Long.parseLong(id)); 
		
		//客户端IP
		String ip = request.getLocalAddr();
		
		//得到文件真实路径
		ServletContext context = request.getSession().getServletContext();
		String filename = context.getRealPath(data.getFile_url());
		
		//新的文件名+扩展名
		String newname = data.getOldname()+"."+data.getExpand();
		
		try {
			// 此文件是否存在
			String path = filename;
			File file = new File(path);
			if (file.exists()&&data.getData_status()!=5) {
				//存在的情况下，设置response参数
				response.setContentType("application/force-download");
				String oldname = URLEncoder.encode(newname, "UTF-8");
				oldname = newname;
		        if(request.getHeader("user-agent").indexOf("MSIE") != -1) {   
		        	oldname = java.net.URLEncoder.encode(oldname,"utf-8");   
		        } else {   
		        	oldname = new String(oldname.getBytes("utf-8"),"iso-8859-1") ;   
		        }
				response.setHeader("Content-Disposition",
						"attachment;filename=" + oldname);
				response.setContentLength((int) file.length());
				//参数设置结束
				
				//文件进入输入流
				InputStream in = new FileInputStream(file);
			
				//设置输出流 为response
				OutputStream out = response.getOutputStream();
				
				//设置缓冲区并读出
				byte[] b = new byte[1024];
				int len = -1;
				while ((len = in.read(b)) != -1) {
					out.write(b, 0, len);
				}
				out.close();
			} else {
				System.err.println("你下载文件已经不存在...");
			}
		} catch (Exception e) {

		}


		
	}

二、java中压缩文件，并下载，实例链接：
http://blog.163.com/chiyunjuan@126/blog/static/34119412201182055051171/